The present invention relates to a zoned heating and air conditioning system, and especially to an air handling system having special dampers used in connection with separate thermostats to heat or air condition one zone while disabling another.
In the past, there have been a number of systems suggested for controlling the temperature in different portions of a building with different thermostats or for disabling one portion of a building when that portion of the building is not in use. Typically such systems use two air conditioning compressors along with two duct systems, one controlling the temperature in the bedroom portion of a house and the other controlling the temperature in the living room, dining room and kitchen portion of a house. In this way the bedroom portion can be heated or cooled in the evenings with the temperature adjusted during the daytime to reduce the energy usage in that portion of the house. Similarly, the remainder of the house can be adjusted between nighttime and daytime, and thereby reduce the total energy utilized. It has also been suggested to open or close air grills to disable one or more rooms for long periods of time so that energy is not wasted heating or cooling an unused room or portion of a house. One of the disadvantages of many prior systems is that they require two separate air conditioning systems, or alternatively, require expensive electrical systems for working different portions of the building. The present system overcomes some of the disadvantages of prior systems by providing a single heating and cooling system of a substantially reduced size for a building while maintaining the comfort level of those portions of the building in use. For instance, the heating and air conditioning system can be reduced in size to provide only half as much energy as required for the full building. The duct system would be similar in cost and complexity to an existing duct system with the building set up to operate the heating and air conditioning system only in that portion of the building in use at any particular time, and to shift from one system to the other prior to using the other part of the building. The present system also provides for inexpensive dampers electronically controlled to reduce the cost of the system to well below the cost of a heating and air conditioning system for the entire building.
Typical prior art U.S. patents can be seen in the Perkins U.S. Pat. No. 3,994,335, for a multizone air conditioning system using a thermostatically controlled valve system in the air ducts to control the amount of hot and cold air delivered to each zone of the building. Similarly, the Marshall, et al., U.S. Pat. No. 3,368,752, uses a spool valve to control cool air and the mix of cool and hot air in a dual duct air conditioning system with seasonal changeover assembly. Prior air conditioning grill dampers and air duct control systems can be seen in the U.S. patent to Waeldner, U.S. Pat. No. 3,604,625, on an air flow mixing device for air conditioning systems using a solenoid controlled system of interconnected valve members, and in the Downes, Jr., U.S. Pat. No. 4,418,719, for an air control apparatus using a drive motor to shift vanes. The Marks, et al., U.S. Pat. No. 4,055,954, shows a damper actuator for ventilator systems in which a temperature expansion cylinder is used for controlling the damper. The Felter patent, U.S. Pat. No. 4,017,026, is for an automatic damper which has a temperature responsive element for pivoting semicircular vanes. The Maxson patent, U.S. Pat. No. 4,397,223, is an air distributor with automatically closing dampers and the Waterfill patent, U.S. Pat. No. 2,999,640, is an air conditioning mixing valve in which the air flowing past the pipe is aspirated to adjust the valve with a negative pressure in a shifting valve system.
In contrast to these prior patents, the present invention is directed towards a centrally controlled system which will operate dampers in combination with the controls to maintain the temperature in one zone of a building while shutting off another zone of a building and requiring a less expensive installation and a reduced use of energy in the building.